Fire extinguishing process and method



United States Patent 3,464,921 FIRE EXTINGUISHING PROCESS AND METHOD Werner G. Erler, Bielfeldstr. 5, Hamburg-Altona, Germany, and Siegfried Gerber, Schillingskoppel 5f, Hamburg-Sasel, Germany No Drawing, Filed June 13, 1966, Ser. No. 556,922

Int. Cl. A62d 1/00 US. Cl. 2522 13 Claims ABSTRACT OF THE DISCLOSURE This invention generally relates to fire extinguishing and is particularly directed to a novel composition in dry powder form, suitable for extinguishing fires.

Fires are usually classified as to groups or classes. In the United States, class A, B, C and D fires are thus generally recognized, wherein class A refers to fires of paper, wood, textile, rubbish and the like, class B to fires of flammable liquids which have a tendency to ignite, class C relates to fires of electrical equipment, while class D indicates metallic fires. Similar classifications have been adopted in other countries. In Germany, for example, class A fires refer to glowing fires, i.e. fires developing red heat, while class B relates to liquid fires. Class C, in turn, indicates fires of gas under pressure, and class D has reference to metal fires including radiation fires. Accord ing to the German classification, class E refers to fires of electrical equipment.

The inventive fire extinguishing composition is suitable for combatting fires of all classes, and in doing so, one or several of the components of the composition may be correspondingly varied to increase the eifectiveness of the fire extinguishing composition for a particular class of fire.

It has previously been suggested to combat metal fires with a fire extinguishing agent which essentially consists of an inert material such as sodium chloride and an organic substance which has a tendency to carbonize or char, as for example a mixture of hard or dry pitch and an easily flammable material as, for example, polyethylene or hard paraflin. In order to improve the flowability, trickling or pouring capacity of the material and to increase the water repelling characteristics, such prior art compositions have also been admixed with talcum powder, tricalcium-phosphate or stearates. These prior art fire extinguishing compositions have, however, several significant disadvantages. Hard pitch, polyethylene or hard paraflin are diflicult to process into a fire extinguishing composition, their characteristics are greatly dependent on the prevailing heat conditions and, moreover, they have a pronounced tendency to adhere to each other. During grinding and mixing of these components, unavoidable temperature increases thus easily result in lump formation. The adhesion tendency of the powder particles of finely ground inorganic material leads oftentimes to lump formation. This tendency is, of course, significantly increased in respect to thermoplastic organic materials.

Patented Sept. 2, 1969 Accordingly, it is a primary object of this invention to overcome the disadvantages of the prior art fire ex-- tinguishing powders and to provide a fire extinguishing composition which has pronounced fire combatting properties, superior to those of the prior art compositions.

Another object of this invention is to provide for a fire extinguishing material in dry powder form, which is easily prepared and which has no pronounced tendency to form lumps but has superior flowability and may be stored for prolonged periods of time without deterioration.

It is an object of this invention to provide for an improved method of combattin g fires.

Briefly, and in accordance with this invention, the inventive fire extinguishing powder comprises a mixture of inert components such as, for example, sodium chloride and of a certain proportion of lignin sulfonate. The preferred lignin sulfonate is calcium lignin sulfonate which may be obtained in the form of powderous sulfite cellulose liquor residues. A suitable lignin sulfonate in the form of the calcium salt is particularly contained in cellulose or pulp powder from beech or pine wood. Such powder is available on the market and is a waste product of the pulp industry. It is available in large quantities. Since it has no other useful purpose, it is consequently very inexpensive.

Calcium lignin sulfonate has two chemical characteristics which make it eminently suitable as a component in a fire combatting composition. Calcium lignin sulfonate is thus particularly rich in respect to carbon and on the other hand is particularly poor in respect to oxygen. This, of course, means that it has a strong tendency to carbonize. Further, the calcium sulfate remains in admixture with the carbon upon carbonizat'ion. In respect to metal fires, this mixture forms a crust on the metal or metal oxide which adheres to the surface of the burning material. This crust, in turn, prevents re-ignition until sufficient cooling has taken place. An additional advantage of the calcium lignin sulfonate is the expansion characteristic of the cellulose or pulp powder upon heating. The powder thus becomes inflated or swells to a considerable extent which, of course, significantly contributes to the fire combatting. Moreover, the novel fire extinguishing powder is compatible with foam.

Experiments have been carried out with an inert powder which was admixed with 10 to 30% by weight of cellulose or pulp powder containing calcium lignin sulfonate. All these experiments resulted in a spontaneous extinguishing of sodium, magnesium and aluminum fires. The same successful results were obtained in respect to electrical fires.

In further developing the invention, it has been ascertained that the beneficial properties of the inventive fire extinguishing powder may be further increased by admixing the powder with a protein hydrolysate in powder form. The protein hydrolysate admixture yields particularly favorable results in respect to incandescent fires or glowing fires developing red heat.

Furthermore, fluxing agents may be admixed with the inventive powders. Magnesia usta levissima is thus a very suitable fluxing agent for the inventive purpose. The small magnesia crystals possess a prong-like structure with a plurality of jags. They therefore position themselves on the surfaces of the larger organic powder particles. The mechanical adhesion which in fine powders has a tendency to cause lump formation is therefore entirely prevented. Instead of magnesia, or in addition to magnesia, other inorganic chemicals with flow agent characteristics may be used.

Furthermore, it is recommended to admix the inventive powder with a hydrophobing agent, advantageously a silicon dioxide in sub-microscopic fine form, whose particles are coated with methyl groups or hydrocarbon groups which are chemically bonded or anchored on the surface. By siliconization, the flowability and pourability can be improved.

In respect to the inert substances as contained in the fire extinguishing powder, chlorides, particularly sodium, potassium and barium chloride, preferably in a eutectic mixture, are suitable for the inventive purposes.

Experience has demonstrated that the use of lignin sulfonate, particularly in the form of a dry powder obtained from sulfite cellulose liquor residues, yields particularly excellent results in the combatting of metal and radiation fires. This is so because of the formation of strongly adhering crusts which are formed due to the high heating of the powder. These crusts are sticky in a wide temperature range. This counteracts the disadvantage normally inherent in dry powders. The whirling up of dust is thus minimized and consequently does not transmit radiation particles to the extent as is otherwise the case with the use of dry powders.

The inventive fire extinguishing powder is also particularly suitable for combatting aircraft fires. In such fires, metal and liquid fuels usually burn simultaneously. Prior to this invention, no effective means of extinguishing such a combination fire by a single fire extinguishing agent was known. With the known dry extinguishing powders or with foam, the liquid fire could generally successfully be combatted while for combatting the metal fire, the known metal fire extinguishing powders were used. The use of the latter, however, rendered the combatting of the fuel fires more difficult. By contrast, the use of the inventive powder, particularly with a mixture of powderous calcium lignin sulfonate and protein powder, makes it possible quickly to extinguish the metal fire whereupon subsequently the burning fuel can be combatted with foam and also by surface emulsification and finally even by water as extinguishing agent, since the two inventive components, to wit, sulfite cellulose liquor and protein hydrolysate themselves are foam forming water-soluble substances. The foam which is formed from the powder by mixing with entraneous foam or water is, contrary to the known nozzle discharged foams, of very viscous consistency and adheres well to surfaces. In this manner, also slanted or vertical surfaces are effectively covered. This is of great importance in aircraft fires.

The particle size of thet powder is not of great importance in respect to the extinglishing effect, particularly in respect to metal fires. However, the particle size should, if possible, be within the framework of the customary commercially accepted sizes. In order to increase the bulk weight, up to about 10% of heavy spar or barite may replace a corresponding amount of chlorides or the like inert substances.

In order to minimize disturbing dust formation to the greatest possible extent, it is recommended to spray the powder onto the fire in the form of a fan-like jet. Such jet may be produced, for example, by a nozzle provided with a deflector plate.

Experience has demonstrated that l to 40% by weight of calcium lignin sulfonate in the powder gives excellent results. In respect to the protein powder, amounts from 1 to 60% by weight are suitable. Relatively small amounts of magnesia usta levissima have the desired results. Thus, 0.5 to 5% by weight are suitable.

The addition of carbonates" or bicarbonates is also suitable to improve the fire extinguishing characteristics, particularly in liquid fires.

The invention will now be described by several examples, it being understood, however, that these examples are given by way of illustration and not by way of limitation and that many changes may be effected without affecting in any way the scope and spirit of the invention as recited in the appended claims.

Example I A fire extinguishing powder suitable for extinguishing fires of all classes has the following composition:

Percent by weight Calcium lignin sulfonate in powder form 16 Protein powder (ground or obtained by extraction, for example keratin decomposed with lime and dried in an atomizer) 5 Magnesia usta levissima l Talcum powder 6 B203 Or B407Na2 dry NaCl, KCl and/or BaCl dry 50 Hydrophobing agent 2 Example II The following composition proved to be particularly suitable for liquid fires:

Percent by weight Calcium lignin sulfonate in powder form 12 Protein powder (ground or obtained as extract powder, for example keratin decomposed with lime dried in an atomizer) 5 Magnesia usta levissima l Talcum powder 6 Calciumhydrogen phosphate 16 Sodium bicarbonate 58 Hydrophobing agent 2 While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In a fire extinguishing composition in dry powder form, wherein alkali metal chloride is admixed with additives, the improvement which comprises that the composition contains an effective amount of lignin sulfonate in powder form to combat fire, said lignin sulfonate being a sulfite liquor residue and consisting predominantly of calcium lignin sulfonate.

2. The improvement as claimed in claim 1, wherein about between 1 to 40% by weight of said lignin sulfonate are contained in the composition.

3. The improvement as claimed in claim 1, wherein the composition additionally is admixed with a protein hydrolysate.

4. The improvement as claimed in claim 1, wherein the composition additionally contains a fluxing agent, said fluxing agent being magnesia usta levissima.

5. The improvement as claimed in claim 1, wherein the composition additionally contains a hydrophobing agent, said hydrophobing agent being a silicon dioxide in sub-microscopic fine form whose particles are enveloped with methyl groups or hydrocarbon groups which are chemically anchored on the surface.

6. The improvement as claimed in claim 1, wherein the alkali metal chloride is a chloride of sodium or potassium.

7. The improvement as claimed in claim 1, wherein the alkali metal chloride is a chloride of sodium, potassium and barium in eutectic mixture.

8. The improvement as claimed in claim 3, wherein the composition contains about between 1 to 60% by weight of said protein hydrolysate.

9. The improvement as claimed in claim 4, wherein the amount of said magnesia usta levissima is about 0.5 to 5% by weight.

10. A method of combatting a fire which comprises spraying on the fire a dry powder containing alkali metal chloride and lignin sulfonate, said lignin sulfonate being a sulfite liquor residue and consisting predominantly of calcium lignin sulfonate.

11. A method as claimed in claim 10, wherein the powder is sprayed in the form of a fan-like jet.

12. A method as claimed in claim 10, wherein the powder which is sprayed onto the fire is converted into a viscous foam by water or foam added to the fire.

13. The improvement as claimed in claim 10, wherein the powder additionally contains carbonate or bicarbonate to improve the fire extinguishing action.

References Cited UNITED STATES PATENTS 2,800,449 7/ 1957 Browning 252-8.5 2,802,783 8/1957 Weiss et al 2528.5 5 3,258,423 6/1966 Tuve et al 2023 MAYER WEINBLATI, Primary Examiner US. Cl. X.R. 106-15;117--136,137, 138; 260-1243 

